Lantus dosing is based upon how LOW the dose is taking a cat. We don't increase a dose because a preshot number is high. That's hard for people to wrap their heads around, but the most important number in regards to dose is how low the dose causes the cat's BGs to go.
I think it was fine that you stayed with the 2.0u tonight. I'd suggest making a practice of trying to chase how low the dose is taking Oz. When you get a blue midcycle like you did today, get another test in an hour or so. If it's still going down, get one more test in another hour. Once you see it begin to rise, then you'll be confident how low he's going.
We have cats (Sienne's Gabby is one) that can go from amps 400 to pmps 400, but drop to 40 in between. If you look at JD's, you'll see he can (and does almost every cycle) go from amps 500 to less than 100 midcycle and back to pmps 500.
In case you're not familiar with how bounces work, it's described in the
second post in this thread. I think the 406 you saw last night was the apex of the most recent bounce. Probably he got a little lower than the 138 the day before, which is what set him off. I can't tell if he cleared the bounce earlier this afternoon or if he's still in the process of clearing it. Even if a cat is not in danger of going low, more tests still give more information. Although I have to say you do a pretty great job of getting tests in, Ian.
You don't want to automatically bump up his dose every 3 days - you want to re-evaluate it every 3 days. Look at the nadirs and compare them to the part of the protocol guidelines that i quoted earlier. See where most of his nadirs are, look at the recommendations on how long to wait if the nadirs are in that particular BG range, and then make the appropriate increases. This can be trickier than it sounds, so feel free to ask for help making these decisions until you get the hang of it. Most people do want help for the first few months til they get the hang of it.
At this point, I think you could probably increase by 0.25u.
