This time of year in the Northern hemisphere, many buns go a little crazy. This happens to desexed buns as well as intacts buns, although it will be more marked (pun half-intended) with intact buns. It’s the increase in the amount of daylight that affects the bunny endocrine system, i e hormones. Even desexed buns have some production of testosterone in their adrenal glands, and daylight also shuts down the production of sleep hormone (melatonin). It’s jokingly called “March hare syndrom”, and it’s normal.
This could contribute to your bun’s change in behavior. It doesn’t necessarily happen every spring. My bun Bam got March Hare Syndrom one spring only, he’d been neutered for a little over a year that time.
The differential would be pain/ discomfort. Is he eating his hay? Sometimes when a rabbit has molar spurs, the rabbit will start chewing non-food, like cardboard or furniture. You also tend to see changes in food preferences. If this continues, it’d be a good idea to have his molars checked.