Boat 94 was shot up pretty bad on January 29, so there may have been repairs that would have kept it out of service for a week or two.
Which is perfectly OK. But with all the off time and training time I'm wondering how mich time he really spent "on the rivers". I mean if you take his 4.5 months and subtract 1 month for training, 2 weeks in January where he went to Saigon, another 2 weeks while his boat got fixed up, he wasn't on the rivers that much.