I'm replacing an inner tie rod on the left side of my 2005 Sierra SLE crew 2WD 5.3L with rack & pinion steering. When I removed the inner tie rod boot, steering fluid came out, not very much maybe half a shot glass. Is this a problem or is a small amount acceptable?

As long as its not leaking while assembled you should be alright just make sure to check your fluid level when your done and add as needed

The seal is leaking from the high pressure end of the rack, sounds like you don't have much to worry about right now, I had a Nissan that leaked a similar amount for the 8 years I owned it, it never got any worse, I just topped up the P/* reservoir whenever it needed some.
Roger.