I've checked around, nothing specific about this. I'm interested because I agree with you that temp readings can be very helpful in diagnosis and early warning of issues.
At this point, I'd recommend opening an SR to get your problem documented. I suspect that it's an issue with the API or maybe the IPMI driver, but that's really a guess at this point.
If you do open an SR, please PM me the SR number so I can track and contribute?