Shoot it. One grain isn't going to blow anything up.

Short story... literally 2 weeks ago I loaded 300 rounds of 9mm 124gr w/ 5.0gr HP-38.

They shot fine. Zippy, but no pressure signs. So I tried loading some 124gr w/5.5gr HP-38.

These also shot fine. Extra zippy, but no pressure signs. Primers looked good, so I shot the remaining 100 of the 5.5gr loads.

We'll, coincidentally, I checked the Hodgdon online reloading site and the load there was posted at 3.4gr - 4.4gr HP-38.

You could pull all the rounds or just shoot them They aren't double charged.

You could load a couple duplicate rounds and test fire them. My guess is they will be spicy but not dangerous.