I took my car to get an inspection and an oil change 2 days ago and ever since then,I noticed the oil pressure while driving is around 50 or so.I rememebr it use to always be around 60 driving.Is this anything to worry about? Do oil weights matter? Perhaps they used a diffrent weight of oil.

Oil weight, and age both play a role on oil pressure. Perhaps they put in a lighter oil than was previously in there. Should be able to look at the receipt, and see what they put in.