Maybe due to some family bond, he may have some reaction(feeling) regarding his capture compared to reacting to some random person.
But nothing other to be worried about, not even current Luffy would care too much about Garp capture like he cares for Ace capture at this stage. None of them owe each other lives
If anybody is in danger, none would care to help unless they are in same place/island or close by. They all follow their own (different) path, it's none their business to reach out for each other.