Question
I just seeded with both rye grass and fescue grass seed.  I have level ground and I watered very thoroughly.  No puddling has occurred even though I left the water on for quite a long period.  It is a bit late to have seeded but I didn't realize that before I prepared the site and put the seed down.

I know that I need to keep the seed wet until after germination about 3-4 weeks.  The question I have:  is it possible to water too much on this well drained site?

Answer
It is possible to drown grass (seedlings) or cause diseases introduced by too much water.  Do not over fertilize.  Use bare minimum for late seeding.  However, if you are in the south, it is late for rye.  Fescue may do well enough.
Watering will cool the soil, thus helping germination and survival.  Rye should be up in two weeks; fescue in three to four.  Good compost topdressed (1/4")will increase germination and survival as well as furnish nutrients as the lawn requires.  Don't worry.  If lawn does not do well, overseeding in fall will thicken it up.  Wait until cool weather (50-70 deg F.) to overseed.
Contractors in NC must plant fescue lawns 365 days a year.  You can too.