Currently my level is 32 and according to this thread (http://forum.team17.co.uk/showthread.php?t=60026) at Level 30-39, my max ammount of reinforcements should be 19.

But in the last log in I was awarded with a total of 23 as you can see in the screenshot below:

http://i.imgur.com/pBG3c.jpg

You can have more than the "Maximum" reinforcements (16 at levels 1-9, 17 10-19 etc..) but if you do then you won't get a free one every 5 minutes.

the number is in green, which means you got excess reinforcements

you probably got some as daily login bonus...

you probably got some as daily login bonus...

Yes, or just a charity bug xD

Maybe you got some as gifts or daily rewards! Lucky boy! ;)