Do you happen to know if there is a limit as to how many questions or links can one submit?

Yesterday I came up with a message "You are submitting too fast. Slow down please. Thanks". I waited a few minutes but it persisted. In the end I tried after an hour, two, before I went to bed and finally I posted today.

I tried posting this message around midday (an hour after my last post) and could not - the same message kept on appearing. I tried different computers, cleared cache etc. nothing. Finally 6 hours after my last submission I managed to post it (hopefully I am not the only one seeing it :))

So the question is, what is the limit on submissions. How many per hour and what is the time in between?

Is it just me or others experience the same?

Thank you for your help in advance.