Well, you don't have an oil pressure gauge on it, and that would be the easiest way to tell. Maybe they put too thick of a grade of oil in it. I'd check your receipt if I were you, and possibly call the shop and ask them what weight they used (if they remember). Like I said earlier, why amsoil? Honda doesn't reccommend using it. I can't say that it harms anything, but I think amsoil is overkill for imports. I'd use it in 4X4's, but not in a 4 cylinder.

In order to check the sump, like I said earlier, you have to pull the oil pan. It's held on with 2 bolts, and you'll need a new gasket. You should be able to see crap clogging the screen in it if that's the problem. Clean it by soaking it in gasoline, then blow it out with compressed air.