Repeat deep cleaning, scam or necessary?

I recently moved to New York and visited my new dentist for the first time just prior to Thanksgiving in November. It had been over a year since I last visited a dentist (my bad I know) so I was somewhat apprehensive about the visit. However, my dentist was great and on inspection said that, apart from plaque build up, my teeth were fine. I wasn't expecting him to find any issues with my teeth (as I'm 25yrs old and have never really had any dental problems - not even a cavity) but I was expecting him to bring up the plaque build up which was visible even to me looking at my lower jaw in the mirror, so I was passed on to the dental hygienist for prophylaxis.

The hygienist went to work on cleaning as much as she could within the session and did a pretty good job (visible to me the next day looking in the mirror) but recommended that I do a deeper clean. Given how much time had lapsed between my last visit to the dentist, I heeded her advice and scheduled a scaling and root planing session in January. The prophylaxis session was free as part of my dental coverage but I would need to pay a $200 copay for all 4 quadrants of my mouth for the deep clean session, to which I agreed.

The deep clean session was just as uncomfortable as the prophylaxis but I soldiered through it and was glad to be done with it last week and from what I can see, my teeth and gum line also look very clean now. Before leaving the dental office, I agreed to a follow up in April (3 months from now) with the expectation that it would just be a quick check up to see how my teeth were doing post cleaning. However, I just received another co-payment approval in the mail indicating that my insurer had approved another deep cleaning session for my April visit. I am a little surprised by this because it seems a little excessive to have another deep clean in 3 months after already having completed a regular and deep session within the prior 3-month period!

Does this sound like a money making scam for another $200? Surely if my teeth were in such dire straights, I would have been called in sooner for another session? The deep clean specialist did not sound at all alarmed when I left last week. Should I call my insurer and ask for a second opinion from another dentist's office? Wouldn't another (free) regular cleaning session be a more reasonable next step prior to embarking on another deep clear!? Smells fishy to me.

Any advice or past experiences shared would be greatly appreciated. I am happy to pay for dental services (I just forked out $200 of my own) but I hate being taken for a ride by unscrupulous providers - who lure you in with free annual check ups and semi annual cleanings and then clean out your wallet!

Thanks in advance!