In HP and the Order of the Phoenix Dumbledore sends Hagrid and Maxime off on a mission to try to win the trust of the remaining giants. It seems that large amounts of enforced proximity and shared hardships has worked its usual magic;
‘Madame Maxime went with you, then?’ Hermione interjected. ‘Yeah, tha’s righ’,’ said Hagrid, and a softened expression appeared on the few inches of face that were not obscured by beard or green steak. ‘Yeah, it was jus’ the pair of us. An’ I’ll tell yeh this, she’s not afraid of roughin’ it, Olympe. Yeh know, she’s a fine, well-dressed woman, an’ knowin’ where we was goin’ I wondered ’ow she’d feel abou’ clamberin’ over boulders an’ sleepin’ in caves an’ tha’, bu’ she never complained once.’
Note also that much of her grumpiness in the HP:GoF seems to centre around her unwillingness to admit to being a giantess. By HP:OOtP it appears that she's come to admit (at least to Dumbledore and his close allies) that she has giant heritage.