Last week the internal scrobbling option in Deezer was lagging for several hours, see the main thread about scrobbling in this forum. So it is possible that this is the reason why you miss scrobbles. When Deezer caught up the queued scrobbles and submitted them later, they probably did not have the original timestamp anymore, but rather the one when they were submitted to your Last.fm user profile. So you can check your Last.fm library if you can find them anywhere.
To avoid problems with the internal Deezer scrobbling, you can also use external scrobbling apps, they are available for Android devices and the web player in a desktop browser.