Bad deal.

you asked to fix the leak or replace the seal?!

 

Subject of wide interpretation on how much to do. Old days, shop would have examined the work, considered best to do to "FIX" the problem.
Now, drop pan, stick on gasket. No consideration for when the oil may have been coming from above, or a nice gouge in the edge of the pan.

 

I agree that's the proper way, verify the customer's diagnosis was correct. Seems like these days some shops will take the customer at their word, do the requested repair and then kick it out the door without actually verifying it.

The fact there was oil dripping down onto the ground afterwards kinda makes me think maybe it was a front structure leak or a front crank seal and not the pan gasket.

Dunno what engine OP has other than its a "CAT" but I bet that foamy stuff they're seeing is some kind of sealant where the front structure meets the block or, in the case of a puzzle-piece pan gasket, sealant where the pieces of pan gasket are joined.

 

What you should do is clean the oil pan and surrounding areas and let the truck idle to make sure it’s the actual oil pan leaking and not something else. If it’s the pan than they can fix their mistake. If it’s not than take it somewhere else, I know it’s hard to find a good mechanic in this country since the standards are very low for everything, but find a decent one and stick to him. Preferably one who does same makes and same engines on daily basis. Will save you a lot of trouble in the long run.