As we know,the wallet did not has any sync problem. Maybe sometime is just during the stake generate  time,hence many transactions just come in the same time,hence wallet will appear to out of sync problem,but don't worry,it will fix itself just a little time

And we need to make some notification to both of us,same as others POS coins,since the stake generate  everyday,so we need to open our wallet everyday,if you been long time not running your wallet,it may bring some bad thing such as zero confirm for some incoming coin,and that problem could not be solve.
Hence please insure to keep your wallet open everyday for your stakes!