Using oil,and cant find where.

I have an 01 Forester I purchased used.
The agreement of terms upon purchase was to
have the motor resealed.
Headgaskets,valvecover,intake,waterpump,timing
belt,and exhaust......exc.
It has been a good driving car put 4500 hundred
miles on it after purchase.Drove to Bangor,and
down to the coast.No problems as far as driving
and starting.
I had a crack and a small part of the air filter
assembly missing which caused rough idling.
I've sealed and fixed the problem.
The other issuse is that is used over two quarts of
oil since purchase.Got it when it had 170k
It has 174, and changed at 172,500.
Put Castro Gtx high mileage 10-30.
Since changing oil I have put the 5th at from the
bottle I bought,and yesterday another half quart.
No smoke upon start,no valve cover leaks.
I have a seaping from the pan which was
changed"supposivly", and can see that it was
RTVed, and not sure about new gasket.
See seepage,but drips in driveway, and to me
minor seapage on the pan.
Should I be worried?