var %blah = $regex($1-,/got posted (.*?) ago by/iS)
This assumes $1- has the text line, strips color codes and ignores case (iS) and gives the time you wanted in $regml(1), until you do another $regex or $regsub.
The var %blah is just used to get rid of the output of $regex, you can check if it actually matched or not, but then you better use if ($regex(..)) { ... } immediately
if you want all numbers separately:
var %blah = $regex($1-,/got posted (\d+d |)(\d+h |)(\d+m |)(\d+s |)ago by/iS)
where $regml(1) has number of days or is $null if none, $regml(2) is hours, ... $regml(4) is seconds or $null if not present
