If you are on your period, brownish discharge towards the final days of your period CAN be normal. It is old blood.

However, it can also not be..depending the person.

If you're not on your period, it is more so something to worry about.

I'd suggest calling and/or visiting your doctor and describing more what it was like (texture, any smells, time, how long it lasted, etc.) And asking if that is normal or if you should go in for a visit because it could possibly be something serious. It is better to prevent than to lament.