As was stated earlier, it depends on the standard errors. If you have a small dataset with a lot of variability the regression lines might cross on a graph but the interaction term might not meet your level of statistical significant. Consider the following plot, where the different colors represent theoretical data from participants of different genders:
Each dataset only has 10 observations, and fitting a regression model to the table results in the following stats:
Estimate Std. Error t value Pr(>|t|)
(Intercept) 8.4922 1.6514 5.143 9.83e-05 ***
time 0.6303 0.2661 2.368 0.0308 *
gender 2.1139 2.3354 0.905 0.3788
time:gender -0.5282 0.3764 -1.403 0.1796
Hopefully that helps!