It doesn't look as if its trying to swallow it so I think the suggested explanation is probably logical.
The two pairs that nested on the Isle of Wight (UK) and raised 8(?) young in 2014 didn't return this year. Some people had suggested they might as Bee-eaters are supposedly site-faithful, however that no doubt applies in their main breeding range and not to just a couple of overshoot pairs. They didn't come back anyway.