I don't ever recall seeing outer tank temperatures less than inner tank temperatures in flight.
Been flying A320's and A330's since 1992, and can recall that on the
A320 temperature differences between the outer and inner tanks are quite common. However, it's not a series issue even for the type of extended operations that are being discussed here, Reason, that outer tank fuel remains in the outer tanks until the inner fuel is down to a predetermined level. Then, it is basically dumped into the inner tank where it is mixed with fuel that is much warmer.
A321's are different, as they do not have an inner and outer. A330's are significantly different, as the fuel moves around all over the place.