Buyers want something fixed after closing

[Collin Luckett]

Hello, we sold a house and during the final walkthrough the buyers noticed the well pump leaking. To close, we agreed to get it fixed within 10 days after closing.

The first plumber that came out took a look and didn’t see anything leaking. The sellers insisted it was so we had a second guy come out. We had him replace a gasket even though he didn’t notice anything. This was within 10 days.
2 weeks later and the buyers messaged and said it was still leaking. After looking at it, it’s not really leaking or dripping, more so just a little moisture around the seal. More like “seeping” than leaking at best.

Do I get someone out again to look at it? It seems so minor and if it were us I know we wouldn’t think twice about it. How do I address it with the buyers if it isn’t really a “leak”? Are they being silly or am I?