Take it back and have him measure the travel on the balljoint. Every
balljoint has some verticle movement, some vehicles allow more than
others in their specs. Blazers are horrible. Their lowers are allowd
an eighth of an inch of movement.
Here in Pennsylvania, a PA State Safety Inspection Mechanic must have
a dial indicator to check balljoint runout. I have a list of
acceptable measurements at the shop, but you can find that list at
MOOG site.

A bad balljoint typically will not show too many symptoms. Sometimes,
when turning you may hear/feel a clunk, usually when turning and
backing up.

If your balljoints are bad, you should have them replaced, and then
have the vehicle aligned. Your tires will thank you.