Without seeing more midcycle numbers, it is impossible to tell, but he sure could be bouncing from lows to highs. 4.2 looks too high for the 350s to me. I am wondering if 90 was on the way down, or did he drop lower than that overnight? I'd argue your 417 could definitely be a bounce, not necessarily that you didn't give enough insulin this am.
The more data, the more you can figure out his patterns and whether the cycles are high and flat or whether there is an early or late low in there causing bounces. If you'd like help with that, we'd be glad to try but please attach your spreadsheet to your signature.