Is my coolant temp too low?

[riorust]

I recently replaced the alternator on my 190E 2.6. In doing so, I disconnected the two coolant hoses to the water pump to gain better access to the tensioner bolt. The upper hose was dry ( engine was cold), I did lose several quarts of coolant (estimated by the spill on the floor)when I disconnected the lower hose.

I completed the alternator job, re-tensioned the belt, topped off the coolant, ran (about 5 min) and burped the system (via the bolt on the t-stat housing)( w/heat on full), now my temp gauge wont hit 80 degrees (seems to stay in the upper 70's) after a 2-4 mile drive. I'm in the Los Angeles area and the temps have been in the 60's during the day.

Is this normal? Or did I get an air pocket? I don't put more than 4k miles a year on my cars....do I need to give a longer distance run ( maybe get a social life?)?