Actually, I am glad you shot the full dose, that was the right thing to do. If you read the SLGS guideline in dealing with lower than normal preshot number, it says "until you collect enough data to know how your cat will react". And the part of the SLGS guideline that you are thinking of regarding options when you see preshots between 150-200 also says "There's no hard and fast rule, but if you don't have data on how your cat responds to insulin..."
You've shot similar numbers before and were able to gather data to see how those cycles went. Again, it is a guideline particularly for newer caregivers who do not have enough data. You can gradually think about shooting at even lower numbers, provided of course that it is over 90 if you are following SLGS.
That said, since you haven't seen a blue preshot in a while, I'd probably see where Leo is at around +1 or +2. I appreciate you are doing SLGS, but even with this dosing method, catching a before bed test helps to fill in the missing pieces. When you only test during the am cycle, you are only getting half the picture. A before bed test last night would have been interesting - it is hard to see whether he was still dropping down to this morning's preshot, or perhaps he had a lower number last night, and may be starting a bounce this cycle, which is why I'd see about getting a +1 or +2 and go from there depending on the BG number(s) you get.
. Well, interesting +1.75, that earns a reduction to 0.5u for the next shot. Can you feed a couple of teaspoons of his regular food, and test again in 30-45 minutes? He's still doing fine, but I'd like to see him flatten out a little now, since there's still a lot of the cycle left to go.