Saitama clearly likes getting credit and being appreciated. However, I believe the reason he did that in this particular situation, is because he cared more about how the civilians were viewing the other heroes and didn't like the way they were belittled despite them putting their lives on the line. We sort of see this from Saitama, especially after Mumen Rider gets beaten up by Deep Sea King. Saitama clearly knew the former at least in terms of power, was practically useless. However, he is still appreciative and acknowledges the effort put in by Mumen Rider as you can see here.
Another important factor to note is that, unlike other professional heroes, Saitama doesn't walk into a fight with anything at stake or anything to lose. He isn't in a situation where his life is at risk or he's doing something extremely difficult compared to the rest of the Heroes where they are literally putting their lives on the line. We can see this side of him when he's surprised that his ranking went up significantly after smashing the meteor which he didn't consider as big of a deal.
Saitama deep inside, strongly believes in the role of a professional Hero and what it represents. Another similar incident is when he fights Suiryu and the latter undermines being a hero (which you can see here at 15:24, when they talk about the hero job.), Saitama gets serious and is very offended and reacts in a particular manner. Hence, in conclusion, Saitama strongly stands for the Hero association and the role that it entails and acknowledges the level of effort put in by heroes and was clearly upset with the way the public were treating them. Also, while to an ordinary person, Saitama's feats might seem unbelievable and monumental, to Saitama they aren't. In other words, one could say Mumen Rider for instance has much more at stake and put in more effort in comparison to Saitama(Who Despite being a million times more efficient), barely put in any effort.
