dovecot - May 2014 - Disconnected from database, retrying commit?

In my log I have a lot of log entries like this one (covering one hour of logs
here):

May 15 09:00:49 dict: Info: maildatabase: Disconnected from database, retrying
commit
May 15 09:17:10 dict: Info: maildatabase: Disconnected from database, retrying
commit
May 15 09:22:30 dict: Info: maildatabase: Disconnected from database, retrying
commit
May 15 09:31:07 dict: Info: maildatabase: Disconnected from database, retrying
commit
May 15 09:37:15 dict: Info: maildatabase: Disconnected from database, retrying
commit
May 15 09:39:36 dict: Info: maildatabase: Disconnected from database, retrying
commit
May 15 09:50:49 dict: Info: maildatabase: Disconnected from database, retrying
commit

7 times per hour, that's quite a bit. Dovecot 2.1.17

Related logs look like:
======================
May 15 00:16:44 imap(username): Info: save: box=Sent, uid=1196,
msgid=<5373EB4A.90306 at sys4.de>, size=11152
May 15 00:16:44 dict: Info: maildatabase: Disconnected from database, retrying
commit

or:

May 14 16:10:34 lmtp(7225, username at domain): Info: NTuhEvF1c1M5HAAAcnFQ7Q:
msgid=<20090714161800.121200 at gmx.net>: saved mail to INBOX
May 14 16:10:34 dict: Info: maildatabase: Disconnected from database, retrying
commit
May 14 16:10:34 dict: Info: mysql(sql.sys4.de): Connected to database
maildatabase

So it's reconnecting, but why is it disconnecting/being disconnected
in the first place? Does it matter? should I worry?

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