Amex automatically increased my CL to $3K

I have a pretty recent credit history in the US as I started building credit April of last year.

I have an Amex Card since August 2016 that granted me $1k in credit. I asked for an automatic 3x CL in November 2016 and got rejected. However, last month, they automatically increased it to 3k.

As my last manual CL request was in November 2016, do you know if I should ask for a 3x CL increase again as it was more than 6 months ago? Or it won't work because they increased it automatically last month?

Thanks guys!