Would the motor mount be covered under the 100k mile power train warranty? What mileage were you at when the mechanic noticed it during the lifter replacement?
It's 5 years / 100,000 miles so if the engine work was recent, the 5 years are up.
Out of all the vehicles I've owned, my 2007 Suburban LTZ has by far had the most problems. I keep a maintenance log of all my cars. My 2011 Challenger has 15 entries. My 2002 Ram 1500 has 20 entries. Mostly oil changes and routine maintenance. No major repairs.
My 2007 Suburban has 170 entries, many of which were major repairs. My dash is cracked. My door handles are peeling again. The motor mounts are a pain to do but I've done both. It's amazing what a difference they made in quieting the engine noise inside the cabin.
I do all the work on my vehicles myself so I have no labor costs which helps considerably.
I know the mechanics of the suburban so well that even with all the problems, I'm considering getting a used one for myself. Probably one with bad lifters so I can get an even better deal. Paying someone to do a lifter repair job is very expensive labor wise but very inexpensive if doing the job yourself.